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re: Asilisaurus kongwe, the Oldest Avian-line Archosaur and the Early Diversification of Ornithodira
David Peters <email@example.com> wrote:
> Any dino precursor with leaf-shaped teeth, a beak-like
> lower jaw and a quadrupedal stance has three strikes against
> candidacy for the avian lineage.
OK, I'll bite...
The Silesauridae was not directly ancestral to Dinosauria. Or to birds. The
Silesauridae is the sister taxon to Dinosauria (according to this analysis,
Basal dinosauromorphs were not simply a "dinosaur factory". Each individual
taxon (lagosuchids, lagerpetids, silesaurids) was free to branch off and
acquire its own characters, independent of those characters that dinosaurs
(including birds) acquired later. Your next statement (below) tells me you
probably understand this concept; so I really don't understand why you then
claim that silesaurids are precluded from "candidacy for the avian lineage".
> These all denote offshoot
> characters from the recurved tooth, non-beak-like lower jaw,
> bipedal ancestor of birds and silesaurids
> But then, if the paper says otherwise...
The authors are using the term "avian lineage" to differentiate the clade
(Ornithodira, or more properly Avemetatarsalia) from the "crocodilian lineage"
(Crurotarsi or Pseudosuchia). Try not too read too much into the "avian" part
of the term.
> I'm seeing problems with the inclusion of basal taxa
> (pterosaurs, Lagerpeton) that are unrelated to the lineage
> of dinosaurs. Might be part of the problem.
In this instance, I think the problem(s) might be yours alone. I cannot see
any justification for excluding lagerpetids and/or pterosaurs from a
phylogenetic analysis of the Archosauria.